Wash-fast water-repellent cotton fabric and method



United The present invention relates to the production of cotton textile fabrics having a high degree of water repellency, which is retained after laundering.

Cotton fabric has been difficult to make durably water repellent with silicones because clothing made from such fabric is normally laundered in soap and Water, and after such washing, the water repellency initially afforded by the silicone applied by methods known to the prior art is reduced to a point of little value.

One object of the invention is to provide a silicone treated, water-repellent cotton fabric in which the water repellency is substantially fast to laundering. Another object of the invention is the provision of methods for treating cotton fabrics with silicones in combination with other materials to provide wash-fast Water repellency in the treated product. Other objects of the invention Will be more readily apparent from the following detailed description of the invention.

Broadly stated, the objects of the invention are accomplished by treating a cotton textile fabric with both a repellency retainer and a silicone.

The word silicone will be used throughout this specification as a term of convenience to mean the liquid linear methyl hydrogen polysiloxanes chain stopped with trimethylsiloxy groups as defined in Wilcock U.S. Patent No. 2,491,843 of 1949.

The term repellency retainer is used for want of amore definitive term to describe the classes of materials within the scope of this invention which will so alter the properties of cotton fabric that they will retain substantially all of the beneficial properties of a Silicone treatment on subsequent laundering.

The repellency retainers may also be considered as silicone binders or cellulose modifiers, but inasmuch as there is no known explanation for their unexpected advantages, the broader term is considered more appropriate.

The repellency retainers may be defined as basic (as opposed to acidic), nitrogen containing, water soluble or acid soluble, non-hydrophilic film forming prepolymerized compounds and their acid salts, including among others, deacetylated chitin, dicyandiamidine formaldehyde hydrochloride, guanidine formaldehyde, the reaction product of .epichlorohydrin and ethylene diamine, an acid co-polymerization product of urea formaldehyde and l,3-dimethylol-5-ethyl-2( l -s-tetrahydrotriazone, and an acid polymerized melamine formaldehyde condensation product. The term acid soluble as used above means that the repellency retainer is soluble in dilute acid solutions although not necessarily soluble in strong acid solutions.

These compounds are to be disinguished from the monomeric products of the prior art by the fact that they are polymerized prior to application to the fabric in each instance to a prepolymer at least as high as a trimcr and preferably considerably higher. They are further to be distinguished from the substantially neutral resins of the prior art suchas urea formaldehyde and ethylene urea formaldehyde (1,3-dimethylol imidazolidone-Z).

The repellency retainers are further characterized by the fact that they are substantive to the cellulose and do not require subsequent polymerization to bind them.

sates atent k 3,038,821 Patented June 12, 1962 They lie on the surface of the fiber rather than within it. More specifically stated, the objects of this invention are accomplished by impregnating a textile fabric with a repellency retainer and a silicone as defined above and a catalyst for the silicone, and curing the silicone.

Some of the repellency retainers appear to give somewhat better results if applied as a pretreatment; however, in the interest of economy of production, it is often preferable to impregnate the fabric by passing it through a single aqueous bath containing both a suitable repel lency retainer and a silicone with its catalyst.

In addition to the primary advantage of providing consistent fastness to laundering for silicones, this invention is also characterized by economy, efficiency, simplicity and the elimination of undesirable side eifects. It is especially significant that good results are obtained with from about 0.1% to 0.5% solids by weight (on the basis of the treating solution) of the repellency retainers. Prior attempts to accomplish the same purpose with essentially monomeric aminoplast resins have utilized from about 1% to 10% of the resin on the same weight basis.

it is obvious that the use of a single impregnation is more efiicient than a two bath operation. It has also been found that the use of the repellency retainers of this invention tends to overcome variations in preparation of the fabrics for a water-repellent treatment which heretofore caused erratic results, thereby simplifying mill operations as a whole. The repellency retainers also enable the production of high initial spray ratings on silicone treated naphthol dyed fabrics which has been a major problem in the past so that water repellency is no longer a function of the type of dye.

The amount of repellency retainer added to the fabric should be at least about 0.05% by Weight (on the Weight of the fabric). There is no critical upper limit of repellency retainer, but as a practical matter, one will use no more than 10% on the weight of the fabric.

In the actual treatment of the textiles, the step of applying the silicone is carried out in accordance with the prior art, namely impregnating the fabric with from about 50% to of its own weight of an aqueous bath containing from about 1% to 6% of a silicone emulsion (usually about 60% solids) and any suitable catalyst, usually a tin containing catalyst (preferably /2% to 3% based on the weight of the bath of an emulsion of tin oleate containing about 6% tin), drying the impregnated fabric, and curing the fabric at from about 300 F. to 350 F. for from about 1 to 5 minutes. The improvement step of this invention is the addition of a repellency retainer to the fabric, either by pretreatment or by inclusion in the silicone bath or by both means.

When a pretreatment is involved, the fabric is impregnated by being passed through an aqueous bath containing the desired repellency retainer and dried. Curing is not necessary.

Stabilized emulsions of silicones are sometimes difficult to obtain with some fo the repellency retainers and in such instances it is usually preferable to use those repellency retainers as a pretreatment rather than to risk the re-wetting danger of an over application of a strong emulsifier. Deacetylated chitin, particularly as the acetic acid salt, is completely compatible with silicone emulsions, and this, among other reasons, makes it the preferred repellency retainer of the invention.

The invention will be better understood by the following typical examples.

EXAMPLE A Silicone Emulsion Methyl hydrogen polysiloxane fluid, supplied as General Electric Silicone Fluid 81268, was emulsified by mixing 50 parts of 81268 with 10 parts of a 10% solution of polyvinyl alcohol, supplied as Elvanol Grade 5042 by E. I. du Pont de Nemours. To this oil phase was added with constant stirring 40 parts of water. After complete addition of the water, stirring was continued uninterrupted for 45 minutes after which this premix was colloided to o/W over a colloid mill. The final emulsion with pH adjusted to 4.55.5 was stable to storage and dispersible in all concentrations in water. Other emulsifiers which work in this system include Igepal -530, Ethomid 0/15, and blends of these emulsifiers.

EXAMPLE B Catalyst Emulsion Tin oleate, supplied as Silicure T-795 by Nuodex Products Co., was emulsified by dissolving 800 parts T-795 in 350 parts xylene, and mixing in 210 parts of a solution of Elvanol Grade 50-42. To this was added a mixture of 100 parts of 37% formaldehyde and 665 parts of water. After a mixing period of 45 minutes, the emulsion was colloided to o/w over a colloid mill. This emulsion was dispersible in all concentrations and was stable to storage and it contained 6% on a weight basis of tin in the form of tin oleate.

EXAMPLE 1 A dicyandiamidine formaldehyde condensation product was prepared by heating together 500 pounds of muriatic acid (48% HCl) and 1400 pounds of water to 135 F. Thereafter 500 pounds of dicyandiamide were added and the temperature rose to between 185 19S F. without added heat. This mixture was cooled to 175 F. and 520 pounds additional muriatic acid (38% HCl) was added with stirring. Thereafter, an additional 500 pounds of dicyandiamide was added. The reaction was exothermic and the temperature rose to between 205 F. and 210 F. The mixture was cooled to 200 F. and 1480 pounds of Formalin (37% formaldehyde) was added and this mixture was allowed to cool overnight to form the final product which had about 27% solids.

A prepared cotton fabric running bout 2.5 yards per pound was padded at 55% wet pickup with 3% of the product prepared as described above. The fabric was dried at 250300 F. to a moisture content of approximately 3%, whereupon it was padded at 55% wet pickup with 4% silicone emulsion prepared in accordance with Example A and 1.6% tin oleate emulsion as described in Example B. After drying at 250300 F., the fabric was cured 2% minutes at 350 F. The fabric so treated had an initial spray rating of 100 as determined by AATCC Spray Rating Test Method 2241, and this spray rating was 80 after five launderings in a home washer at 150 F. using Tide (a built alkyl aryl sulfonate) as detergent. Fabrics treated with silicone and tin oleate but without the dicyandiamidine resin were 90100 initially, but the spray rating was zero after five launderings.

EXAMPLE 2 A solution of Kylan 100LV, deacetylated chitin, was prepared by dissolving 4- pounds of Kylan 100LV in a solution of 92 pounds of water and 4 pounds of acetic acid. This resulted in a viscous solution soluble in all concentrations in water.

A prepared cotton fabric 2.5 yards per pound was treated at 55% wet pickup with 4% of the Kylan lOOLV solution prepared as described above. After drying at 250300 F., the fabric was padded with 4% of the silicone emulsion described in Example A and 1.6% of the tin oleate emulsion as described in Example B, dried 250300 F., and cured 2% minutes at 350 F. The fabric so treated had an initial spray rating of 100 and a spray rating of 7080 after five launderings.

EXAMPLE 3 A prepared cotton fabric Weighing 6 ounces pe square 4 yard was padded with 4% of a solution of Kylan LV as described in Example 2, 4% of a silicone emulsion prepared in accordance with Example A, and 1.6% of a tin oleate emulsion as described in Example B at 55 wet pickup, dried at 250300 F., and cured 2% minutes at 35 0 F. The fabric so treated had an initial spray rating of 100 and maintained a spray rating of 7080 through five launderings.

EXAMPLE 4 A polymeric urea-formaldehyde-triazone formaldehyde product was prepared by mixing 1125 pounds of UF-85 concentrate, Allied Chemical Co. (urea formaldehyde containing 59% formaldehyde and 26% urea), with 45 pounds of urea. To this was added with stirring 360 pounds of 70% ethylamine, keeping the temperature below 145 F. with cooling. After complete addition of the amine, the temperature was raised to 160 F. and held for one hour. While still hot an additional 610 pounds of UF-85 concentrate and 208 pounds of urea were added to the reaction kettle and the pH adjusted to 4.5, whereupon the entire mass Was heated to 165 F. for 1 hour and 45 minutes. The product was then cooled to F. and pounds of water added. After adjustment of the pH to 5.56.0, the product was drawn off for storage. *1

A prepared cotton fabric was padded at 55 wet pickup with a 4% aqueous solution of the product prepared as described above. After drying at 250300 F., the fabric was padded with 4% of the silicone emulsion described in Example A and 1.6% of the tin oleate emulsion prepared in accordance with Example B, dried at 250-300 F., and cured 2% minutes at 350 F. This fabric had an initial spray rating of 100 and this spray rating was 80 after five launderings.

EXAMPLE 5 A prepared cotton fabric was padded at 55% wet pickup with 4% of the product prepared in accordance with Example 4, 4% of the silicone emulsion described in Example A, and 1.6% of the tin oleate emulsion prepared in accordance with Example B. After drying at 250-300 F. and curing 2% minutes at 350 F., the fabric had an initial spray rating of 100 and on washing the water repellency was shown to be retained.

EXAMPLE 6 A prepared cotton fabric was padded with an aqueous solution containing 3% Inpad Resin T-106, a polymeric melamine formaldehyde resin supplied by Imperial Paper and Color Corp., at 55% wet pickup and dried at 250- 300 F. The fabric was then treated with 4% of the silicone emulsion prepared as described in Example A and 1.6% of the tin oleate emulsion prepared in accordance with Example B. The initial spray rating was 100 and permanency was evidenced by maintenance of an 80 spray rating after five washings at F.

EXAMPLE 7 A polymeric substance suitable for use in this invention was prepared by adding 46.3 parts of epichlorohydrin to 32.5 parts of 92% ethylene diamine dropwise, maintaining the temperature at 212 F. Fifty parts of water were added after the mixture became thick. After addition of all components, the products were heated at approximately 220 F. for 30 minutes. Final product was a thick, light brown fluid.

A cotton fabric running 2.5 yards per pound was padded with 10% of the product as described above and dried at 250-300 F. This pretreated fabric was then padded with 4% of the silicone emulsion prepared as described in Example A and 1.6% of the tin oleate emu1- sion prepared in Example B, dried at 250300 F., and cured 2% minutes at 350 F. The fabric so treated had excellent initial water repellency which Was maintained through washing.

EXAMPLE 8 A prepared cotton fabric was padded at Wet pickup with 4% of the Kylan IOOLV solution described in Example 2, 5% of the silicone emulsion described in Example A, 2% of the tin oleate emulsion as outlined in Example B, 12% of a 50% solution of dimethylol ethylene urea (cyclic), and 1 /z% of a solution of zinc nitrate. The fabric after drying and curing showed excellent water repellency initially, and a spray rating of after 5 home launderings.

It will be realized that the improvements afforded by the present invention are generally applicable with all silicones useful in the treatment of cotton fabrics for Water repellency. The examples are confined to the use of General Electric Silicone Fluid 81268 only because it appears to afford best results on cotton fabric. It is merely one of several available liquid linear methyl hydrogen polysiloxanes chain stopped with trimethyl siloxy groups. It is characterized by a maximum viscosity at F. of 50 centistokes, an average molecular weight range of 700-1400, and a specific gravity at 20 C. of .98.99.

The gist of my invention is the application to fabric of a basic, polymeric material in small quantity in combination with a polysiloxane and a heavy metal soap or salt to produce on the fabric durable Water repellency. The polymeric material may be applied either as a pretreatment or with the silicone, the one bath process being limited only by bath compatibility.

We claim:

1. In the treatment of cotton textile fabric to provide repellency to water wherein the fabric is impregnated with an aqueous emulsion containing a linear liquid methyl hydrogen polysiloxane in which the chain is stopped with trimethylsiloxy groups and a curing catalyst therefor, and the thus impregnated fabric is dried and cured, the improvement of imparting wash-fastness to said repellency which comprises depositing on the surfaces of the fibers or" said fabric, deacety-lated chitin solubilized with an acid, said chitin being deposited in an amount of at least 0.05 percent based on the dry Weight of said fabric.

2. The process set forth in claim 1 wherein said deacetylated chitin is deposited on said fibers at the same time that the fabric is impregnated with said polysiloxane and dried.

3. The process set forth in claim 1 wherein said acid is acetic acid.

4. The process set forth in claim 1 wherein said deaeetylated chitin is deposited on said fibers prior to impregnation of said fabric with said polysiloxane.

References 'Cited in the tile of this patent UNITED STATES PATENTS 2,224,293 Finlayson et al. Dec. 10, 1940 2,559,221 Maxwell et al. July 3, 1951 2,612,482 Rasmussen Sept. 30, 1952 2,661,313 Folkers Dec. 1, 1953 2,758,946 Spalding Aug. 14, 1956 2,774,749 Stanley et a1 Dec. 18, 1956 2,807,601 Dennett Sept. 24, 1957 2,826,500 Keim Mar. 11, 1958 2,839,429 Marsh et a1 June 17, 1958 2,842,509 Shannon July 8, 1958 2,844,490 Lehmann et a1. July 22, 1958 2,901,463 Hurwitz Aug. 25, 1959 FOREIGN PATENTS 458,813 Great Britain Dec. 21, 1936 

1. IN THE TREATMENT OF COTTON TEXTILE TO PROVIDE REPELLENCY TO WATER WHEREIN THE FABRIC IS IMPFEGNATED WITH AN AQUEOUS EMULSION CONTAINING A LINEAR LIQUID METHYL HYDROGEN POLKYSILOXANE IN WHICH THE CHAIN IS STOPPED WITH TRIMETHYLSILOXY GROUPS AND A CURING CATALYST THEREOF, AND THE THUS IMPREGNATED FABRIC IS DRIED AND CURED, THE IMPROVEMENT OF IMPARTING WASH-FASTNESS TO SAID REPELLENCY WHICH COMPRISES DEPOSITING ON THE SURFACES OF THE FIBRES OF SAID FABRIC, DECETYLATED CHITIN SOLUBILIZED WITH AN ACID, SAID CHITIN BEING DEPOSITED IN AN AMOUNT OF AT LEAST 0.05 PERCENT BASED ON THE DRY WEIGHT OF SAID FABRIC. 